Yarn delivery devices are used to draw off the yarn from a yarn supply, for example a bobbin, and to deliver it to a yarn-consuming arrangement, for example at a preset yarn speed, or at a preset yarn tension, or with other preconditions. Such yarn-consuming arrangements can be knitting stations of knitting machines, or other mechanical arrangements. Elastic yarns, inelastic yarns made of natural fibers or synthetic fibers, staple fiber yarns, other yarns or monofilaments are considered to be yarns. Often the yarn consumption location does not consume yarn at a constant rate. For example, such is the case when the yarn consumption location is switched on or off, for example in connection with loop or Jacquard machines. Friction feed wheel units are known for this, wherein the yarn is looped around a rotating drum, but is lifted off the drum at one or several locations. For example, U.S. Pat. No. 2,539,527 discloses a yarn delivery device whose yarn delivery wheel consists of a drum-shaped rod cage. Two hook-shaped spiral springs are arranged in the vicinity of the rod cage, which partially lift the single yarn winding looped around the drum off the rod cage. The looping characteristics of the rod cage change with different yarn tensions because of the deflection of the spiral springs.
Another yarn delivery device is known from French Patent 964 455. That yarn delivery device has a rotating yarn delivery drum. A yarn is looped several times around the drum. The individual yarn loops created in this way also loop around two pivotably seated pins, which extend next to the yarn delivery drum either parallel or at an acute angle relative to the drum, depending on the pivot position. This allows the pins to be pivoted away from the drum in order to increase the yarn reserve when the downstream located knitting station does not take on yarn. With this device, the looping characteristics also change because of the movement of the pins.
A yarn delivery device is also known from USSR Patent 785168. This device has a rotating cylindrical yarn delivery drum and a yarn lifting element assigned to the drum. The yarn lifting element has a kinked yarn contact surface, with a first section that extends at an acute angle of 15° to 20° relative to the drum surface and a second section that extends parallel to the drum surface. The lower end of the yarn lifting element is forked, with a machine shut-off lever entering into the space between the tines of the fork. Because of the kink between the upper part and lower part of the contact surface, the individual windings looped around the lifting element and the drum have different lengths. Therefore, a strong or a weak yarn pull therefore is not easily propagated evenly through all windings.
There is often the desire to operate a yarn delivery device in different modes of operation. However, the above-mentioned prior art devices are arranged either as positive feed wheel units with a yarn supply, or as friction feed wheel units. It has also been noticed that the commercially available devices must be adapted to the yarn to be delivered. This is a considerable limitation, and the removal thereof is of primary importance.